Alias is an American action thriller and science fiction television series created by J. J. Abrams that was broadcast on ABC for five seasons from September 30, 2001, to May 22, 2006. It stars Jennifer Garner as Sydney Bristow, a double agent for the Central Intelligence Agency posing as an operative for SD-6, a worldwide criminal and espionage organization. Main co-stars throughout all five seasons included Michael Vartan as Michael Vaughn, Ron Rifkin as Arvin Sloane, and Victor Garber as Jack Bristow.

The first two seasons of Alias mainly explore Sydney's obligation to hide her true career from her friends and family as she assumes multiple aliases to carry out missions as well as her efforts to take down SD-6 with the help of the CIA. The series' later seasons deal with multiple character and plot driven storylines, with a recurring focus on the search for and recovery of artifacts created by Milo Rambaldi, a fictitious Renaissance-era figure with similarities to both Leonardo da Vinci and Nostradamus.

Alias was well received among critics and has been included in several "best of" lists, including the American Film Institute's top ten list for television programs in 2003. The series also received numerous awards and nominations. Alias is considered to be part of a wave of television series from the late 1990s and early 2000s that feature strong female characters, alongside Buffy the Vampire Slayer, Charmed, Xena: Warrior Princess, La Femme Nikita, Veronica Mars, and Dark Angel.